Blender animation fbx export to Unity incorrect Hip bone movement

I created some simple reload animations in Blender and wanted to try them out in Unity. However it appears that in Unity my character’s hip bone moves in this floaty manner even though in blender’s keyframes it is set to constant 0.

https://www.youtube.com/watch?v=I2eI5EFyZjI

Not only that, but I have to translate root by 99.4 (??) and rotate it by -60 degrees in import settings. I have no idea what went wrong, I have done some animations before and it worked well (except rotating).
But this is less important, I am concerned about hip bone moving even though clearly it’s keyframed at 0. Other bones move fine.

It appears that importing an M4 model into blender to help me align animation caused it. It looks like the hip bone is influenced by IK bones and constraints used in blender. However I export an fbx file from blender and into Unity with only the armature and model, as I am interested in only animations.

Why is this happening? It’s so annoying, I can never get these animations to work on first attempt. If there is no easy fix I think I’ll have to redo the whole thing.

Nevermind. I created a new blender file, imported the models and remade animations from scratch. And it works right away.

What happened in the previous file will remain a mystery.